Suppose you're lost inside a cave... In a great feat of luck, you find a cave-link base unit. Nice let's ask for help! You then discover the system is in German and you can't understand how to use it: https://www.cavelink.com/cl3x_neu/index.php/en/component-ove...
Ok, I know it supports other languages, but there's no reason for the main site not to use English to illustrate it. Or better: make the interface intuitive enough that you can use even without reading instructions. We did it with smartphones.
These are highly specialised pieces of technical equipment with a tiny potential market. The use case isn't fixed unattended public installations to be used by untrained randoms, but ad-hoc use by trained users like cave rescue teams and speleologists. As for the UI, production (like much in the caving world) is semi-commercial at best; an iPhone it isn't and frankly it doesn't need to be.
Ok, I know it supports other languages, but there's no reason for the main site not to use English to illustrate it. Or better: make the interface intuitive enough that you can use even without reading instructions. We did it with smartphones.